Drive assembly with interference-fit mounted lightweight non-ferrous pulley

ABSTRACT

A drive assembly for rotating a shaft of a pulley-driven device is disclosed together with a method of making the drive assembly. The method includes the steps of forming a pulley of lightweight non-ferrous metal having a web portion, forming a radially inward portion of the web portion into an axially extending annular portion, mounting a connecting ring of ferrous metal having an annular groove in an interior end surface thereof over the axially extending portion of the web portion so that a free end of the axially extending portion extends adjacent the annular groove, cold-forming the free end to fill the annular groove, welding a hub of ferrous material to the connecting ring and machining a central axial bore through the web portion and the axially extending portion thereof and the hub.

RELATED APPLICATIONS

The present application is an improvement on my application Ser. No.08/412,306, filed Mar. 29, 1995, now U.S. Pat. No. 5,576,728 for a DriveAssembly with Interference-Fit Mounted Pulley.

RELATED APPLICATIONS

The present application is an improvement on my application Ser. No.08/412,306, filed Mar. 29, 1995, now U.S. Pat. No. 5,576,728 for a DriveAssembly with Interference-Fit Mounted Pulley.

BACKGROUND OF THE INVENTION

In the aforesaid application, there is disclosed a drive assembly forrotating a shaft of a belt driven device. The drive assembly includes ahub in the form of an annular body of ferrous metal having a groove inan external periphery thereof. A belt driven pulley is provided in theform of ferrous sheet metal and includes a web portion. A structuralconnection is defined between the hub and the pulley web portion suchthat the hub is fixed in abutted relation with the pulley web portion.The hub and the pulley web portion have a bore therethrough defining asingle, machined annular surface. The annular surface is constructed andarranged to engage a periphery of the shaft in an interference-fittedmanner so as to maintain torque transfer to the shaft in the event offailure of the structural connection. The groove is constructed andarranged to be operatively engaged by a pulling tool for removing theannular surface from engagement with the shaft.

While the pulley made in accordance with the principles of the aforesaidapplication disclosure is satisfactory, there is always the need toprovide a pulley which is more cost effective. One way in which suchcost effectiveness can be achieved is to provide a pulley which islighter while maintaining the same or better performance level.

An object of the present invention is to fulfill the need expressedabove. In accordance with the principles of the present invention, thisobjective is achieved by providing a drive assembly for rotating a shaftof a belt-driven device which comprises a hub in the form of an annularbody of ferrous metal having a radially outwardly projecting annularportion, a pulley made of light weight non-ferrous metal, and aconnecting ring of ferrous metal. The pulley has a web portion formedwith an axially extending annular portion at a radially inward positionthereon. The connecting ring is disposed in surrounding relation withthe axially extending annular portion and has a connection therewithconstructed and arranged to rigidify the connecting ring and the pulley.The hub has a connection with the connecting ring constructed andarranged to rigidify the hub with the pulley through the connectingring. The web portion includes the annular extension thereof and the hubwhich has a bore therethrough defining a single machined annularshaft-engaging surface. The shaft-engaging surface is constructed andarranged to engage a periphery of the shaft in an interference-fittedmanner so as to maintain torque transfer between the pulley and shaft inthe event of the failure of either or both of the connections. The huband the connecting ring are constructed and arranged with respect to theaxially extending annular portion to provide an annular space adjacentthe radially outwardly projecting annular portion of the hub of a sizeto allow a pulling tool to enter the annular space and act upon theradially outwardly projecting annular portion to remove the pulley fromthe periphery of the shaft.

Another object of the present invention is to provide a combinationwhich includes the above-described drive assembly and a vehiclehydraulic power steering pump having a drive shaft wherein the singlemachined annular shaft-engaging surface is engaged with the periphery ofthe shaft in an interferencefitted fashion.

Another object of the present invention is the provision of a costeffective method of making a pulley. In accordance with the principlesof the present invention, this objective is achieved by providing amethod of making a pulley which comprises the steps of forming a pulleyof lightweight non-ferrous metal having a web portion, forming aradially inward portion of said web portion into an axially extendingannular portion, mounting a connecting ring of ferrous metal having anannular groove in an interior end surface thereof over the axiallyextending portion of the web portion so that a free end of the axiallyextending portion extends adjacent the annular groove, cold-forming thefree end to fill the annular groove, welding a hub of ferrous materialto the connecting ring, and machining a central axial bore through theweb portion including the axially extending portion thereof and the hub.

These and other objects of the present invention will become moreapparent during the course of the following detailed description andappended claims.

The invention may best be understood with reference to the accompanyingdrawings wherein an illustrative embodiment is shown.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a vehicle accessory and drive assembly combination,in partial section, provided in accordance with the principles of thepresent invention, shown with a hub and a portion of a pulley of theassembly press-fitted to a drive shaft;

FIGS. 2-5 are fragmentary enlarged sectional views of the centralportion of the drive assembly illustrated in FIG. 1, showing successivemethod steps in making the same in accordance with the principles of thepresent invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS

Referring to the drawings, there is shown therein a drive assembly,generally indicated at 10, which embodies the principles of the presentinvention. It can be appreciated that the drive assembly 10 may be usedto drive any shaft-driven device. However, in the preferred embodimentillustrated in FIG. 1, the drive assembly 10 is coupled to a drive shaft12 of a vehicle accessory 14, such as a hydraulic steering pump, waterpump, air injection pump or alternator. A hydraulic steering pump 14 isshown in FIG. 1.

With reference to FIG. 1, the drive assembly 10 includes a pulley,generally indicated at 16, which is made in any known fashion of alightweight non-ferrous metal, as, for example, aluminum, magnesium oralloys thereof. The pulley 16 includes an outer annular section 18providing an outer pulley surface 20 formed with a series of V-groovesconstructed and arranged to cooperate with a poly-V belt of conventionaldesign.

The pulley 16 also includes integral web portion 22 which, as shown,extends radially in central alignment with the exterior peripheralsection 18. It will be understood that the web portion may be laterallyoffset in accordance with well-known practice.

The drive assembly 10 also includes a connecting ring 24 which is formedof a ferrous material as, for example, steel. A third component of thedrive assembly 10 is a hub 26 in the form of an annular body of ferrousmaterial as, for example, steel. Both the connecting ring 24 and the hub26 can be formed in any known manner and preferably both are machinedfrom bar stock although they may be forged.

Referring now more particularly to FIGS. 2-5, there is shown thereinpreferred steps in a method of making the drive assembly 10 inaccordance with the principles of the present invention. It will beunderstood that, while the method to be described is preferred, inbroadest aspects of the present invention, the drive assembly 10 can bemade by other methods than the preferred method which is now to bedescribed.

As best shown in FIG. 2, the web portion 22, at a position adjacent itsradially innermost central portion, is cold-formed to provide an axiallyextending annular portion 28. A preferred cold-forming operation is toeffect the step with cooperating dies. Next, as shown in FIG. 3, theconnecting ring 24 is mounted over the axially extending portion 28 andis positioned in engagement with the web portion 22. As best shown inFIG. 3, the interior surface of the connecting ring is formed with aninterior annular groove 30 which is disposed in spaced relation with theweb portion 22, after the connecting ring 24 has been mounted on theaxially extending annular portion 28. It will also be noted from FIG. 3that a free end of the axially extending annular portion 28 is disposedadjacent the annular groove 30.

In the next step, the results of which are shown in FIG. 4, the free endof the axially extending annular portion 28 is cold-formed so as to fillthe annular groove 30. This step results in the formation of an annularprojection 32 on the exterior periphery of the axially extending annularportion 28 which is disposed within the annular groove 30. Theengagement of the annular projection 32 within the annular groove 30provides a mechanical connection which rigidifies the interconnection ofthe connecting ring with the web portion of the pulley.

FIG. 5 shows the next step in the manufacture of the drive assembly 10wherein the hub 26 is positioned in axially aligned relation with theconnecting ring 24 and pulley 16. As shown in FIG. 5, preferably the hub26 includes an axially facing annular bead 34 disposed in a position toengage an oppositely facing surface of the connecting ring 24 when thehub 26 and the pulley 10 are axially moved toward one another.Preferably, the hub and web portion are then pressed toward one anotherand a welding electrical charge is caused to flow therethrough whichfuses the bead 34 to the connecting ring 24 and provides a weldedconnection between the hub 26 and the connecting ring 24 with the hub 26disposed in engagement both with the connecting ring 24 and the adjacentend of the axially extending annular portion 28 of the pulley 16. In thebroadest aspects of the present invention, other connecting modesbetween the hub and connecting ring may be utilized as well as otherknown modes of welding.

With the drive assembly 10 thus connected together, the hub 26 and webportion 22 including the axially extending annular portion 28 aremachine-bored so as to provide a single machine interior shaftengagingsurface, as shown in FIG. 1. The machining of the shaft-engaging surface36 is coordinated with the dimension of the periphery of the shaft 12 sothat, when the drive assembly 10 is mounted on the shaft 12, the surface36 is engaged with the periphery of the shaft 12 in aninterference-fitted manner. This ensures that there will be asubstantial area of contact between the drive assembly 10 and the shaft12 with a significant amount of contact between the metal of the pulley16 and the shaft 12 which ensures that, if the welded connection betweenthe hub 26 and the connecting ring 24 or the connection between theconnecting ring 24 and the axially extending annular portion 28 shouldfail or, if both should fail, there is still sufficient interengagementbetween the pulley 10 and the shaft 12 to maintain torque transfer.

Any United States patent applications or patents mentioned or citedhereinabove are hereby incorporated by reference into the presentspecification.

It thus will be seen that the objects of this invention have been fullyand effectively accomplished. It will be realized, however, that theforegoing preferred specific embodiment has been shown and described forthe purpose of this invention and is subject to change without departurefrom such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

What is claimed is:
 1. A drive assembly for rotating a shaft of a beltdriven device comprisinga hub in the form of an annular body of ferrousmetal having a radially outwardly projecting annular portion, a pulleymade of light weight non-ferrous metal, and a connecting ring of ferrousmetal, said pulley having a web portion formed with an axially extendingannular portion at a radially inward position thereon, said connectingring being disposed in surrounding relation with said axially extendingannular portion and having a connection therewith constructed andarranged to rigidify said connecting ring and said pulley, said hubhaving a connection with said connecting ring constructed and arrangedto rigidify said hub with said pulley through said connecting ring, saidweb portion including the annular extension thereof and said hub havinga bore therethrough defining a single machined annular shaft-engagingsurface, said shaft-engaging surface being constructed and arranged toengage a periphery of the shaft in an interference-fitted manner so asto maintain torque transfer between the pulley and shaft in the event ofthe failure of either or both of said connections, said hub and saidconnecting ring being constructed and arranged with respect to saidaxially extending annular portion to provide an annular space adjacentthe radially outwardly projecting annular portion of said hub of a sizeto allow a pulling tool to enter the annular space and act upon saidradially outwardly projecting annular portion to remove said pulley fromthe periphery of the shaft.
 2. A drive assembly as defined in claim 1wherein said lightweight non-ferrous metal is aluminum, magnesium oralloys thereof.
 3. A drive assembly as defined in claim 2 wherein theconnection of said hub with said connecting ring is a weldingconnection.
 4. A drive assembly as defined in claim 3 wherein saidwelding connection comprises an axially facing annular bead on an endsurface of said hub which is electrically welded to an adjacent face ofsaid connecting ring.
 5. A drive assembly as defined in claim 4 whereinthe connection of said connecting ring with said axially extendingannular portion comprises an annular groove in an axially outward andradially inward position thereon, said axially extending annular portionhaving a free end cold-formed to fill said groove.
 6. A drive assemblyas defined in claim 5 wherein said pulley includes a poly-Vbelt-engaging exterior surface.
 7. A drive assembly as defined in claim6 wherein said web portion extends radially centrally with respect tosaid poly-V belt-engaging exterior surface.
 8. A drive assembly asdefined in claim 2 wherein the connection of said connecting ring withsaid axially extending annular portion comprises an annular groove in anaxially outward and radially inward position thereon, said axiallyextending annular portion having a free end cold-formed to fill saidgroove.
 9. A drive assembly as defined in claim 2 wherein said pulleyincludes a poly-V belt-engaging exterior surface.
 10. A drive assemblyas defined in claim 8 wherein said web portion extends radiallycentrally with respect to said poly-V belt-engaging exterior surface.11. A drive assembly in combination with a vehicle hydraulic powersteering pump, the power steering pump including a drive shaft, saiddrive assembly comprisinga hub in the form of an annular body of ferrousmetal having a radially outwardly projecting annular portion, a pulleymade of light weight non-ferrous metal, and a connecting ring of ferrousmetal, said pulley having a web portion formed with an axially extendingannular portion at a radially inward position thereon, said connectingring being disposed in surrounding relation with said axially extendingannular portion and having a connection therewith constructed andarranged to rigidify said connecting ring and said pulley, said hubhaving a connection with said connecting ring constructed and arrangedto rigidify said hub with said pulley through said connecting ring, saidweb portion including the annular extension thereof and said hub havinga bore therethrough defining a single machined annular shaft-engagingsurface, said shaft-engaging surface being constructed and arranged inengagement with a periphery of the shaft in an interference-fittedmanner so as to maintain torque transfer between the pulley and shaft inthe event of the failure of either or both of said connections, said huband said connecting ring being constructed and arranged with respect tosaid axially extending annular portion to provide an annular spaceadjacent the radially outwardly projecting annular portion of said hubof a size to allow a pulling tool to enter the annular space and actupon said radially outwardly projecting annular portion to remove saidpulley from the periphery of the shaft.
 12. The combination as definedin claim 11 wherein said lightweight non-ferrous metal is aluminum,magnesium or alloys thereof.
 13. The combination as defined in claim 11wherein the connection of said hub with said connecting ring is awelding connection.
 14. The combination as defined in claim 13 whereinsaid welding connection comprises an axially facing annular bead on anend surface of said hub which is electrically welded to an adjacent faceof said connecting ring.
 15. The combination as defined in claim 11wherein the connection of said connecting ring with said axiallyextending annular portion comprises an annular groove in an axiallyoutward and radially inward position thereon, said axially extendingannular portion having a free end cold-formed to fill said groove. 16.The combination as defined in claim 11 wherein said pulley includes apoly-V belt-engaging exterior surface.
 17. The combination as defined inclaim 16 wherein said web portion extends radially centrally withrespect to said poly-V belt-engaging exterior surface.